Does anyone know an API that generates the Hash images

I've been searching for an API which can g开发者_运维技巧enerate (and i'll need one that can then read) image hashes.

I don't know if that exactly what they are called. They are those black and white crossword looking like images you see on tickets or groceries at the supermarket that uniquely identify something.

Those are not called image hashes, they are regular barcodes, albeit 2-d or matrix barcodes. The reason why they identify things is due to the fact that the barcode contains a unique id, or in the case of matrix barcodes, quite some amount of data.

Popular examples would be the QR-code or Datamatrix. You did not specify any language, so you have to look up compatible libraries yourself, but I guess with the keywords provided here, this will be very easy.

Do you mean barcodes? QR code?

http://fukuchi.org/works/qrencode/index.en.html (c)

http://code.google.com/p/zxing/ (java)

http://www.twit88.com/home/opensource/qrcode (c#)

The word you are searching for is "barcode". The first examples were one-dimensional. They were patterns of bars and spaces that were scanned normal to the bar. Information is coded by the variations of widths of the bars and spaces. One dimensional barcodes have the advantage that they generally require relatively low-precision print processes to form. They have the disadvantage of low information density. Common 1D symbologies include Code 39, UPC-A and Interleaved 2 of 5.

More recent codes use 2D patterns to pack more information into less area. Common examples are the hexagonal MaxiCode symbols seen on UPS packages, and the various square pattern symbols (QR code, Aztec code, Datamatrix are common) turning up on a lot of goods, in postage, and even in advertising.

There are many recognized kinds of barcode (known as symbologies to the industry). Here is a link to a nice concise list with examples of some commonly found symbols.

Most of the vendors of barcode equipment also sell software to generate symbols and labels containing symbols. There are also a number of open source projects, usually focused on a single symbology, or a group of closely related symbologies.